Fuel oil



atented Oct. 1, 1940 UNITED STATES FUEL OIL Garland H. B. Davis, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application January 30, 1937, Serial No. 123,143

5 Claims.

The present invention relates to an improvement in heavy fuel oils and other heavy residual products, containing waxy materials and which have highpour points in consequence, and more specifically to a method of stabilizing the pour points of these materials, and furthermore to oils of that character containing the stabilizing agents. The invention will be fully understood in the following description.

It has been recognized for some time that asphalts and asphaltic materials of the type found in heavy petroleum oils have mild pour inhibiting properties. This pour inhibiting action of asphaltenes has been familiar for some time and has been especially noted by the fact that when asphaltic materials are removed from the residual oilscontaining wax, their pour points invariably rise. Asphaltic materials are not nearly so potent, in respect to pour inhibiting, as the well known synthetics which are now used commercially in refined oils. Furthermore, asphaltenes raise the carbon residue of the oil so that such materials cannot be used in high grade products.

While as noted above the asphaltenes cannot be used in high grade reflned lubricating oils for the reasons already given, it is equally true that the more effective synthetic compounds cannot be used practically in residual fuel oils because of their high cost, but it is possible to use natural asphaltlc materials in fuel oils. The difficulty presented here, however, is that these materials are not stable. The reason for this is not iully understood, but it has many times been observed that fuel oils containing asphalt and was have a low pour point at the time of their production and that over a period of several weehs or months, the pour point gradually rises hy as much as 20", or even 50 F.

it has been noted that this phenomenon seems to be hastened by the cycle of heating and cooling to which the oil is ordinarily subjected in storage. During the day, the temperature of the oil ordinarily rises and during the night it falls to a considerable extent. This alternate heating and cooling gradually causes the pour point of the oilto rise more rapidly than in the case of an oil held at constant temperatures. This phenoinenon is very troublesome to the refiners because it is frequently the case that there are deflnite specifications for pour point, and while the oil as produced may meet this specification, it is iound later to have too high a pour point, and oiten this causes considerable dimculty to the ultimate consumer. One solution to this problem would, of course, be the removal of the wax or of the asphaltic material, but fuel oils are ordinarily sold at such low prices that such treatment must be avoided if possible.

It is found that the instability of pour point in 5 waxy fuels can be to a large extent corrected by the addition to the oil of a small amount of a certain class of materials, namely, the amines. The amine may be chosen from the classes of the aromatic or aliphatic amines which are soluble in the oil, and since only very small amounts are required, it is not necessary that they be very soluble. Amines containing only carbon, hydrogen and nitrogen are useful for the purpose, such as benzidine, toluidines, xylidines and the like, also alpha or beta naphthyl amine or other a1- kylated derivatives. Aniline is not very desirable being quite inferior to benzidines and toluidines. Among the mono-aliphatic amines it is desirable to use those containing more than about six carbon atoms, for example, hexyl amine, in order to prevent their loss by evaporation. Primary, secondary and tertiary amines are used and mixtures of any two of the groups. The poly-amines can be used-quite satisfactorily, or mixtures of them as well. The presence of a hydroxyl group, as in the amine compound, is not objectionable, and in many cases it is found to be highly advantageous, for example, in the case of an amino alcohol such as amino propanols or the alkylolamines.

Aromatic hydroxy amines are also useful, such as amino phenols or the alkylated amino phenols. Thev aromatic amines may also belong to the primary, secondary or tertiarytypes. Mixed amines such as methyl, ethyl or hexyl phenyl amines will also serve the present purpose.

The amount of the amino materials used in the present invention is not large, being in all cases below .5%, and usually between the limits of .01 to 20%. There is generally an optimum quantity for the use of the material which should not be exceeded because if more is used there is a reversal of the desired effect, and the finished material not only has the disadvantage of not having a stable pour point but also shows a marked tendency to precipitate. Within the above range, however, there is a possibility of variation in the amount. Increased amounts generally produce a greater effect, that is, maintain the pour point of the oil below the required temperature for a longer time until the optimum quantity is exceeded. With a satisfactory amount of the agent the pour point may be kept below any reasonable specification such as 20, 30, or

40 F. for six months or more, and it is only in rare cases that fuels are stored for a longer period than this. As examplesof the use of the present invention the following should be considered:

Example I A residual fuel oil, containing both asphaltenes and wax, has on its production a pour point of 20 F. To a sample of this oil is added .05% of diamino propanol. After the addition of this material the pour point was found to be 15 F. The two samples of the oil were then prepared for the following test, the one containing the amine and the other without it:

These samples were subjected to the same heat treatment which consisted in rapidly heating to 105 F. and then cooling to about 15 or 20 F.

The cycle was repeated six times and the pour point was taken according to the standard methods.

The oil containing the amine showed that its pour point rose to 45 F. which was the specification for this particular fuel. The sample which did not contain the amine, however, showed a pour point of 60 F. at the conclusion of the test. The particular oil containing the amine was found to be perfectly satisfactory as a heavy fuel for boilers and the like.

Example II The oils prepared in the previous example were subjected to a second test in which they were heated to 105 F. duringthe day and cooled during the night to F. This test was conducted for one month, repeating the heating cycleeach day. At the end of the test, it was found that the oil containing the amine had a pour point of 10 F. which wasinterpreted to mean that it had not been changed during that period, while the sample which did not contain the amine showed a pour point of 60 F. I

Experiments with tests of this sort showed that the test applied to Example I was somewhat more severe than in Example 11, but if the oil passes satisfactorily through a series of five heating and cooling stages, it would ordinarily be satisfactory for commercial use. The second test more closely simulates the commercial conditions, but it naturally takes longer and is apparently less severe.

Example III To another commercial fuel oil, containing asphaltenes and wax, is added .1% of diamino propanol. The sample showed a-pour test of 10 F.,

unstable character and, therefore, was considered amore diflicult one to handle than that used in the prior examples.

Example IV To a fuel oil containing asphaltenes and wax is added -.01% of alpha naphthyl amine. The pour point originally was 0 F. and gave a test of 10 F. after the addition of the amine. I This 011 was stored for some time and appeared to be much more stable than oils of the same character without the amine.

It is, of course, recognized that amines have been added to refined oils prior to the present invention. These materials are known to have an antioxidizing eifect in refined oils but it is believed that the present function of the amine is quite different from that illustrated in the prior art. The refined oils of the type in which antioxidizing agents have been used' are almost exclusively distilled products, such as gasoline,

kerosene, or lubricating oils, which have been refined soas to be substantially free of asphaltenes. In the present case there is no intention to cover such refined distillate oils but only heavy residual fuel oils of thetypes containing wax and having an unstable pour point due to the presence of asphaltic material. In most instances the asphaltic materials are present in the fuel oils to such an extent that it is not required that any be added to reduce the pour point. However, it is contemplated that if such oils be available in which there is not sufiicient asphaltic material, it may be added together with the amine to accomplish the present purpose.

The present invention is not limited to any theory of the action or combined action of the.

amine and the asphalt inhibitor, nor to any specific type of amine, but only to the following claims in which it is desired to claim all' novelty inherent to the invention.

I claim:

1. An improved fuel oil comprising a heavy oil containing constituents that tend to vary its pour point and a small quantity of benzidene to stabilize the pour point.

'2. An improved fuel oil comprising a heavy oil containing constituents that tend to vary its pour point and a small quantity of hexyl phenyl amines to stabilize the pour point.

3. An improved fuel oil comprising a heavy oil containing constituents that tend to vary its pour point and a small quantity of diamino propanol to stabilize the pour point.

4. An improved fuel oil comprising a heavy oil containing constituents that tend to vary its pour point and a small quantity of an amine of the class consisting of b'enzidene, hexyl phenyl amines, diamino propanol, naphthylamines and mono-aliphatic amines containing more than about 6 carbon atoms to stabilize the pour point.

'5. An improved fuel oil comprising a residual oil containing both asphalt and wax and a small quantity of diamino propanol to stabilize the pour point.

GARLAND H. B. ,DAVIS. 

